宽幅分体箱梁涡振性能及其抑振措施

为研究宽幅分体箱梁桥梁涡激振动特性及其相应振动抑制方法，以某主梁总宽度为64.1 m的分体箱梁大跨悬索桥为工程背景，在均匀流场下对1∶70缩尺比节段模型进行了风洞试验. 首先研究了主梁成桥态在0°、± 3°和± 5°五种不同来流攻角下的涡激振动特性；其次，考察了单一气动措施（包括设置水平气动翼板、封闭中央开槽、隔涡网以及检修车轨道导流板），以及各种组合措施对主梁涡激振动的影响，检验了这些措施对主梁颤振性能的影响. 研究结果表明:宽幅分体式双箱梁在5个风攻角下均发生了竖向自由度涡激共振，其中最不利攻角为–3°，竖向振幅最大值为0.69 m，超过《公路桥梁抗风设计规范》限值的70%；设置隔涡网和采用组合气动措施后，较原始主梁，涡振振幅下降50.7%～98.6%；尽管抑振措施使主梁颤振临界风速降低6%～15%，但仍满足抗风设计要求. 

Vortex-Induced Vibration Performance and Control Measures of Wide Twin-Box Girder

In order to study the vortex-induced vibration (VIV) characteristics and control methods of wide twin-box girder bridges, a long-span suspension bridge with twin-box girder and a total girder width of 64.1 m was modeled in a 1∶70 scale ratio and wind tunnel tests for this model were carried out under smooth flow. Firstly, the VIV characteristics of the girder under five attack angles (0°, ± 3°and ± 5°) were studied; secondly, the effects of single aerodynamic measures, including using a horizontal aerodynamic plate, closed central gap, grids and guide plates on overhaul vehicle rail and the effects of the measure combinations were also studied. Finally, the influence of the above aerodynamic measures on the flutter performance of the main girder is examined. The results show that the vertical DOF vortex-induced resonance occurs at all five wind attack angles. The most unfavorable attack angle is –3°, and the maximum vertical vibration amplitude is 0.69 m, which exceeds the limit of the allowable value in Wind-Resistent Design Specification for Highway Bridges by 70%. The combined use of grid and other aerodynamic measures can reduce the VIV amplitude of the main girder by 50.7%–98.6%. However, these control measures reduce the critical flutter wind speed by 6%–15%, which still meets the design requirements.